Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel of the LTE can be classified into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
The PUCCH is distinguished by using different codes, frequencies, times, or combinations thereof while using the same time-frequency resources. Code division multiplexing (CDM) uses different codes. Frequency division multiplexing (FDM) uses different frequencies. That is, each of user equipments transmits its PUCCH by using different codes and/or frequencies in the same time resource.
It can be said that transmission reliability is more important than transmission capacity in a control channel. This is because when an error occurs in transmission of the control channel, a data channel may be never received or it may have a significant effect on scheduling or HARQ operations. Therefore, a payload of the control channel is generally limited to be less than several bits to tens of bits.
In addition, in the uplink control channel, a peak-to-average power ratio (PAPR)/cubic metric (CM) property is important for power management of a user equipment. The uplink control channel needs to maintain a low PAPR/CM property to ensure long battery standby-time and low battery consumption. For this, LTE uses a sequence having a low PAPR/CM property such as a Zadoff-Chu (ZC) sequence in the control channel.
However, the increase in transmission capacity of the control channel is essential due to the introduction of a new technique such as a multiple input multiple output (MIMO) technique, a multi-carrier technique, or the like.
Accordingly, there is a need for a method capable of increasing transmission capacity of a control channel while maintaining a low PAPR/CM property.